Copper Etching Composition for Display Substrates
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Solution Overview
Problem
Conventional copper etchants for display substrates are unstable at room temperature and have limited capacity for treating multiple substrates, leading to issues with RC signal delay and pattern damage during the etching process.
Innovation Solution
An etching composition comprising phosphoric acid (40-70% by weight), nitric acid (5-15% by weight), and acetic acid (5-20% by weight) with water, which provides stability at room temperature and enhances the etching capacity for copper layers, including copper alloys and semiconductive layers, without using fluorine-based compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a strong oxidizer-based copper etchant is used to etch the copper layer, then the etching effectiveness is improved, but the patterns previously formed in prior processes are easily damaged
Solution Approach 1:
The patent changes the chemical parameters of the etchant by using a mixed acid system (phosphoric acid 40-70%, nitric acid 5-15%, acetic acid 5-20%, water remainder) instead of conventional strong oxidizers. This parameter change enables effective copper etching while reducing damage to previously formed patterns, achieving both high productivity and reduced harmful effects.
2Object-affected harmful factors
If a persulfuric acid-based etchant is used to reduce pattern damage, then the stability at room temperature deteriorates and the number of treatable substrates is limited
Solution Approach 1:
The patent creates a composite etching solution combining phosphoric acid, nitric acid, acetic acid, and water in specific proportions. This composite formulation achieves both stability at room temperature and the ability to treat multiple substrates while minimizing pattern damage, overcoming the limitations of single-component persulfuric acid-based etchants.
3Reliability
If the copper layer thickness is increased to reduce RC signal delay, then the etching capacity requirement increases, but the conventional etchants cannot treat multiple substrates effectively
Solution Approach 1:
The patent optimizes the concentration parameters of the etching solution, specifically using phosphoric acid at 40-70%, nitric acid at 5-15%, and acetic acid at 5-20%. This parameter optimization provides sufficient etching capacity for thick copper layers to achieve low resistance while maintaining the ability to effectively treat multiple substrates, resolving the contradiction between reliability and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The etching composition improves storage stability, increases the number of substrates that can be treated, and maintains the integrity of patterns by controlling etching rates and minimizing damage, while allowing for the etching of multi-layered metal and semiconductive structures.
Implementation Method 1
the resistance of copper against an oxidizer is higher than that of aluminum or chrome, so that a strong oxidizer is required for etching a copper layer
Implementation Method 2
An etching composition includes phosphoric acid (H3PO4) of about 40% by weight to about 70% by weight, nitric acid (HNO3) of about 5% by weight to about 15% by weight, acetic acid (CH3COOH) of about 5% by weight to about 20% by weight, and a remainder of water
Data Source
AI summary
An etching composition and a method of manufacturing a display substrate using the etching composition are disclosed. The etching composition includes phosphoric acid (H3PO4) of about 40% by weight to about 70% by weight, nitric acid (HNO3) of about 5% by weight to about 15% by weight, acetic acid (CH3COOH) of about 5% by weight to about 20% by weight, and a remainder of water. Thus, a metal layer including copper may be stably etched.